Inorganic particulate materials have been incorporated in organopolysiloxane compositions to impart certain properties to the resultant elastomers. For example, boron nitride has been incorporated in organopolysiloxane compositions to provide silicone elastomers which resist degradation when exposed to elevated temperatures. Likewise, boron nitride has been incorporated in organopolysiloxane compositions to enhance the thermal conductivity of the resultant elastomers. This is particularly important since in certain electrical applications, the electrical components generate enough heat to cause a change in the resistance of the electrical components which often causes the electrical circuit to function in an abnormal manner. Therefore, it would be desirable to have an insulating material which can be applied to electrical components and readily conducts heat away from these components. Also, it would be desirable to have an insulating material having improved physical properties as well as increased filler loadings, thereby reducing the material costs.
Filler materials, such as boron nitride have been incorporated in two-component, thermally conductive room temperature vulcanizable compositions. For example, U.S. Pat. No. 3,499,859 to Matherly describes a two-component organopolysiloxane composition containing boron nitride as the primary filler. Also, U.S. Pat. No. 4,292,225 to Theodore et al describes a highly filled two-component composition containing an organopolysiloxane, a boron refractory powder and silica.
Room temperature vulcanizable organopolysiloxane compositions containing various fillers are also described in U.S. Pat. No. 2,843,555 to Berridge and U.S. Pat. No. 3,127,363 to Nitzsche et al. Neither of these patents, however, disclose thermally conductive elastomers containing fillers such as contemplated herein.
It has unexpectedly been found that silicon nitride particles can be incorporated in room temperature vulcanizable organopolysiloxane compositions in increased loadings to form silicone elastomers having improved physical properties and thermal conductivity.
Therefore, it is an object of this invention to provide a thermally conductive room temperature vulcanizable organopolysiloxane composition. Another object of this invention is to provide a highly filled room temperature vulcanizable organopolysiloxane composition which forms an elastomer having desirable physical properties and thermal properties. Still another object of this invention is to provide silicone elastomers having superior thermal conductive properties. A further object of this invention is to provide a two-component organopolysiloxane which vulcanizes at room temperature to form a silicone elastomer having superior thermal conductive properties.